Sterile Neutrino Dark Matter

Hidden in the neutrino sector may be one or more fermions with no standard model interactions that nonetheless couple to neutrinos via new mass terms. Such a particle may be the dark matter, produced in the early universe through matter-suppressed neutrino mixing or matter-enhanced resonant mixing. I will overview the kinetics of relativistic mixed neutrinos in dense environments, and will specify with sterile neutrino dark matter production in the early universe. I will discuss how this candidate alters cosmological structure formation, and may be detected in X-ray telescopes. In addition, sterile neutrino dark matter can provide a handle to probe the physics of the epoch of its creation, the QCD phase transition at high temperature.